OLED glass frit slurry for low-energy laser sealing and preparation method of OLED glass frit slurry

Abstract

The invention discloses OLED glass frit slurry for low-energy laser sealing and a preparation method thereof, and relates to the technical field of OLED glass frit slurry, the OLED glass frit slurry comprises the following components: basic glass frit: V2O5, TeO2, BaO and ZnO; the reinforcing system is prepared from ZrO and TiO2; the photothermal conversion agent is CeO; a thermally stable ceramic filler: cordierite; the dispersing agent is prepared from polyvinylpyrrolidone and sulfonated lignin; the organic carriers including ethyl cellulose, terpilenol and butyl carbitol are introduced into a composite dispersant system by constructing a lead-free glass network and combining the synergistic effect of the photothermal conversion agent and the surface modification filler, and particle aggregation is inhibited by utilizing the synergistic effect of a macromolecular chain and a functional group, so that low-energy laser sealing is realized, thermal damage to an OLED device is reduced, and the service life of the OLED device is prolonged. And meanwhile, the sealing airtightness, the interface bonding strength and the long-term reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of OLED glass slurry technology, and in particular to an OLED glass slurry for low-energy laser sealing and its preparation method. Background Technology

[0002] With the rapid development of display technology, OLED is gradually becoming the mainstream next-generation display technology due to its superior performance. However, OLED devices are extremely sensitive to water and oxygen, which requires sealing technology to have extremely high airtightness and long-term reliability. Although traditional glass fusion sealing technology can provide good airtightness, its high-temperature process often causes irreversible thermal damage to OLED devices. To solve this problem, low-temperature laser sealing technology has emerged.

[0003] Currently, the low-temperature laser sealing materials commonly used in the industry are mainly based on low-melting-point glass powder systems. These materials are typically composed of traditional low-melting-point glass systems such as PbO-B2O3-SiO2, with the addition of some light absorbers to improve laser absorption efficiency. However, this approach still has many shortcomings. First, the melting point and softening temperature of traditional low-melting-point glass systems are still relatively high, requiring higher laser power to achieve effective sealing, which increases the risk of thermal damage to OLED devices. Second, existing light absorbers often have insufficient absorption efficiency in the near-infrared band, resulting in low energy conversion efficiency. Furthermore, these materials are prone to generating bubbles and microcracks during the sealing process, severely affecting the airtightness and long-term reliability of the seal.

[0004] Another key issue is insufficient interfacial bonding strength. Existing sealing materials often exhibit weak interfacial bonding with the glass substrate, leading to delamination during long-term use. This not only reduces sealing reliability but can also allow water and oxygen to penetrate, accelerating the aging of OLED devices. Furthermore, due to the lack of effective stress regulation mechanisms, existing materials are prone to cracking during thermal cycling, further reducing the long-term reliability of the seal. Traditional glass frits, due to their excessively wide particle size distribution, exhibit high porosity (>5 parts) during the pre-sintering stage, and the interfacial bonding between the filler and the glass frit is insufficient, resulting in an airtightness of only 1×10⁻⁶ after laser sealing. -8 Pa·m 3 / s level.

[0005] For example, the low-temperature glass paste and its preparation method disclosed in Chinese patent application No. CN202011605946.2, although the boron-bismuth-zinc microcrystalline glass system can achieve sealing at a low temperature, the Bi2O3-B2O3-ZnO system used has low laser absorption efficiency, high laser power requirements, and a large heat-affected zone width, which can easily lead to thermal deformation of the flexible substrate. In addition, the material still needs to be improved in terms of interfacial bonding strength and long-term reliability. Summary of the Invention

[0006] This application provides a low-energy laser sealing OLED glass slurry and its preparation method, which solves the problems of insufficient laser absorption efficiency, limited interfacial bonding strength, and long-term reliability in the prior art. By constructing a V2O5-TeO2-BaO-ZnO lead-free glass network, combining the synergistic effect of photothermal conversion agent and surface modified filler, and introducing a composite dispersant system, the synergistic effect of polymer chains and functional groups is utilized to inhibit particle agglomeration, thereby achieving low-energy laser sealing, reducing thermal damage to OLED devices, and improving the airtightness, interfacial bonding strength, and long-term reliability of the seal.

[0007] This application provides a low-energy laser sealing OLED glass slurry, which comprises the following components by weight:

[0008] Basic glass material: V2O5 30-60 parts, TeO2 20-40 parts, BaO 5-30 parts, ZnO 5-15 parts;

[0009] Enhancement system: ZrO2 5-10 parts, TiO2 5-10 parts;

[0010] Photothermal conversion agent: CeO2 0.5-2 parts;

[0011] Thermally stabilized ceramic filler: 5-15 parts cordierite;

[0012] Dispersant: 0.5-2 parts polyvinylpyrrolidone, 0.5-1.2 parts sulfonated lignin;

[0013] Organic carrier: 15-25 parts ethyl cellulose, 5-10 parts terpineol, 5-10 parts butyl carbitol.

[0014] Furthermore, the glass transition temperature of the base glass material is 340±5℃, and the crystallization temperature is 420±10℃.

[0015] Furthermore, the sulfonated lignin has a core-shell structure, with a core sulfonation degree of 0.8 mmol / g and a shell sulfonation degree of 3.0 mmol / g, resulting in a core-shell structure thickness ratio of 1:2.

[0016] Further, the preparation of the core-shell structure involves treating lignin sequentially with 5wt% dilute sulfuric acid at 80°C for 30 minutes to sulfonate the core layer, followed by a gradient heating treatment with 20wt% concentrated sulfuric acid at 120°C for 1 hour to sulfonate the shell layer. After dialysis purification, the lignin is spray-dried to obtain the final product.

[0017] Furthermore, polyvinylpyrrolidone comprises short-chain and long-chain components, with the short chain having a mass of 40 kDa and the long chain having a mass of 50 kDa, and the mass ratio of the short chain to the long chain being 3:1.

[0018] Furthermore, cordierite was surface-modified with silane coupling agent KH-550, with a mass ratio of cordierite to silane coupling agent of 95:5.

[0019] Furthermore, the viscosity of the slurry at 25°C is 15-20 Pa·s, and the thixotropic index is 1.4-2.2.

[0020] A method for preparing a low-energy laser sealing OLED glass slurry specifically includes the following steps:

[0021] S1. Basic glass material synthesis: V2O5, TeO2, BaO and ZnO are mixed, melted and quenched, and then ground until D50≤2μm and particle size distribution span<1.5;

[0022] S2. Cordierite surface modification: Cordierite is mixed with a silane coupling agent and dried to obtain surface-modified cordierite;

[0023] S3. Slurry preparation: The base glass material, ZrO2, TiO2, CeO2 and modified cordierite are mixed, polyvinylpyrrolidone and sulfonated lignin pre-dispersion are added, and then mixed with the organic carrier. After planetary stirring and ultrasonic dispersion, the slurry is obtained.

[0024] Further, the preparation of the pre-dispersion involves premixing polyvinylpyrrolidone and core-shell sulfonated lignin, dissolving them in terpineol at 30% of the total terpineol content, and then ultrasonically treating them at 50°C for 15-25 minutes to form the pre-dispersion.

[0025] Furthermore, the paste is screen-printed onto the OLED substrate with a line width of 50μm and a thickness of 10μm; the laser sealing uses an 810nm fiber laser with a power of ≤8W and a scanning speed of 10-25mm / s.

[0026] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0027] Firstly, V₂O₅-TeO₂ forms the glass forming agent; TeO₂ has high polarizability, which can reduce the rigidity of the glass network. V₂O₅ provides a bridging oxygen structure, enhancing the thermal stability of the glass. BaO / ZnO acts as a network modifier. 2+ (Large ionic radius) reduces glass viscosity, Zn 2+(Medium field strength) Balanced thermal expansion coefficient, suitable for OLED substrates; uniform CeO2 dispersion improves absorption efficiency per unit mass, further enhances sealing speed, strengthens particle-substrate interface bonding strength, and increases thermal shock resistance cycles; suitable for various printing processes (screen printing / inkjet / slot coating), expanding linewidth range; in this embodiment, the glass frit slurry uses a lead-free system (V2O5-TeO2-BaO-ZnO), avoiding the use of lead and heavy metal components, improving environmental performance; PVP dispersion and silane coupling agent form Si-OM (M=cordierite) chemical bonds on the cordierite surface, improving interface bonding strength, thereby enhancing density and reliability; laser sealing process is suitable for high-resolution, flexible OLED devices, providing an efficient, environmentally friendly, and highly reliable solution for OLED packaging;

[0028] Secondly, by introducing sulfonated lignin and PVP to construct a synergistic dispersion system, and by using techniques such as charge transfer complex to enhance adsorption, three-dimensional grid lock structure to inhibit aggregation, and dual-mode dispersion process and synergistic regulation of rheological properties, the problems of nanoparticle aggregation, poor slurry stability, weak interface bonding and insufficient process adaptability have been solved. This has achieved uniform particle dispersion, optimized rheological properties, improved interface strength and environmentally friendly and low-energy-consumption encapsulation, improved OLED encapsulation reliability and process flexibility, enhanced process flexibility and stability, enhanced interface strength, and adaptability to the high-precision OLED encapsulation requirements.

[0029] Third, by constructing core and shell structures with different degrees of sulfonation in sulfonated lignin, the problems of insufficient dispersion stability and limited process adaptability caused by uniform sulfonation in Example 2 are solved. The functional zoning of the material is combined with dynamic response, thereby achieving dynamic dispersion, reducing porosity, and enhancing interfacial bonding strength.

[0030] Fourth, by combining PVP molecular weight classification with gradient sulfonation SL synergistic design, the synergistic effect of short-chain pore-filling wetting and long-chain elastic polymerization inhibition is achieved. Among them, the short-chain molecules have small molecular weight and fast diffusion rate, preferentially adsorbing to the micropores on the particle surface. They form hydrogen bonds with CeO2 oxygen vacancies through the terminal hydroxyl group (-OH), filling surface defects, reducing roughness, and achieving rapid adsorption and wetting. At the same time, the short chains quickly penetrate into the interparticle gaps under shear force, reducing local stress concentration. The long-chain molecules form multiple hydrogen bonds (bond energy of about 35kJ / mol) with the sulfonic acid groups of the gradient SL through the pyrrolidone ring of the main chain, increasing the adsorption layer thickness, inhibiting particle agglomeration, and further strengthening steric hindrance. At the same time, the long chains wrap around the particles to form a three-dimensional elastic network, resisting particle migration at high temperatures. Attached Figure Description

[0031] Figure 1 This is an optical micrograph with a scale bar of 50 μm in the field of view after laser sealing of the glass slurry in Experiment 2 of Embodiment 1 of the present invention.

[0032] Figure 2 This is an optical micrograph with a scale bar of 5 μm in the field of view after laser sealing of the glass slurry in Experiment 2 of Embodiment 1 of the present invention. Detailed Implementation

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0034] Example 1: A low-energy laser sealing OLED glass slurry, comprising the following components by weight:

[0035] Basic glass material: V2O5 30-60 parts, TeO2 20-40 parts, BaO 5-30 parts, ZnO 5-15 parts;

[0036] Enhancement system: ZrO2 5-10 parts, TiO2 5-10 parts;

[0037] Photothermal conversion agent: CeO2 0.5-2 parts;

[0038] Thermally stabilized ceramic filler: 5-15 parts cordierite;

[0039] Dispersant: 0.5-2 parts of polyvinylpyrrolidone (PVP);

[0040] Organic carrier: 15-25 parts ethyl cellulose, 5-10 parts terpineol, 5-10 parts butyl carbitol;

[0041] The glass transition temperature of the base glass material is 340±5℃, and the crystallization temperature is 420±10℃.

[0042] The preparation method of the OLED glass slurry for low-energy laser sealing includes the following steps:

[0043] S1. Basic glass material synthesis;

[0044] S11. Weigh out V2O5, TeO2, BaO and ZnO raw materials according to the proportion, mix them evenly and place them in a platinum crucible;

[0045] S12. Heat to 1000-1100℃ in air atmosphere, melt and hold for 2 hours;

[0046] S13. Quench the molten glass into deionized water to form glass fragments;

[0047] S14. Use a sand mill to grind the glass fragments to a D50≤2μm and a particle size distribution span<1.5.

[0048] S2. Cordierite surface modification;

[0049] S21. Mix cordierite powder (particle size D90 < 5 μm) with silane coupling agent KH-550 at a mass ratio of 95:5;

[0050] S22. Dry at 120℃ for 1 hour to obtain surface-modified cordierite.

[0051] S3. Slurry preparation;

[0052] S31. Mix the basic glass powder, ZrO2, TiO2, CeO2 and modified cordierite in a certain proportion;

[0053] S32. Pre-dissolve PVP in 30% of the total terpineol to form a homogeneous dispersion; add it in three portions during stirring, with a 5-minute interval between each addition, to ensure that the particle surface is fully wetted.

[0054] S33. Add the remaining organic carrier (ethyl cellulose, terpineol, butyl carbitol, isopropanol) and disperse in a planetary mixer at 2000 rpm for 30 minutes;

[0055] S34. Adjust the slurry rheological properties to a viscosity of 15-20 Pa·s (25℃) and a thixotropic index of 1.8-2.2.

[0056] S4. Laser sealing process;

[0057] S41. The paste is applied to the OLED substrate by screen printing (line width 50μm, thickness 10μm);

[0058] S42. Using an 810nm fiber laser with a power ≤8W and a scanning speed of 10-15mm / s, a sealed product is produced.

[0059] An experiment was conducted on the above-mentioned Example 1. The glass slurry in Example 1 included the following components by weight: 30 parts V2O5, 20 parts TeO2, 5 parts BaO, and 5 parts ZnO.

[0060] Enhanced system: 5 parts ZrO2, 5 parts TiO2;

[0061] Photothermal conversion agent: 0.5 parts CeO2;

[0062] Thermally stabilized ceramic filler: 5 parts cordierite;

[0063] Dispersant: 0.5 parts of polyvinylpyrrolidone (PVP)

[0064] Organic carrier: 15 parts ethyl cellulose, 5 parts terpineol, 5 parts butyl carbitol

[0065] The glass frit slurry in Experiment 2 comprises the following components by weight:

[0066] Basic glass material: 60 parts V2O5, 40 parts TeO2, 30 parts BaO, 15 parts ZnO;

[0067] Enhanced system: 10 parts ZrO2, 10 parts TiO2;

[0068] Photothermal conversion agent: 2 parts CeO2;

[0069] Thermally stabilized ceramic filler: 15 parts cordierite;

[0070] Dispersant: 2 parts polyvinylpyrrolidone (PVP);

[0071] Organic carrier: 25 parts ethyl cellulose, 10 parts terpineol, 10 parts butyl carbitol;

[0072] The glass frit slurry in Experiment 3 comprises the following components by weight:

[0073] Basic glass material: V2O5 45 parts, TeO2 30 parts, BaO 17 parts, ZnO 10 parts;

[0074] Enhanced system: ZrO2 7.5 parts, TiO2 7.5 parts;

[0075] Photothermal conversion agent: CeO2 1.25 parts;

[0076] Thermally stabilized ceramic filler: 10 parts cordierite;

[0077] Dispersant: 1.25 parts of polyvinylpyrrolidone (PVP);

[0078] Organic carrier: 20 parts ethyl cellulose, 7.5 parts terpineol, and 7.5 parts butyl carbitol;

[0079] The glass slurries and sealed samples prepared in Experiments 1 through 3 were subjected to performance tests. Laser absorptivity was measured using an integrating sphere test (ISO 13468-1); airtightness was tested using helium mass spectrometry to detect helium leakage in the sealing layer; interfacial bonding strength was tested using a micro-tensile testing machine to measure the peel strength between the slurry and the substrate; porosity was analyzed using scanning electron microscopy (SEM) combined with ImageJ software to determine the cross-sectional porosity ratio. The test results are shown in Table 1 below. Optical microscopic observation was performed on the glass slurry after laser sealing in Experiment 2. The optical micrograph with a scale bar of 50 μm in the field of view is shown below. Figure 1 As shown, the optical micrograph with a scale bar of 5 μm in the field of view is as follows. Figure 2 As shown;

[0080] Laser absorption rate (%) <![CDATA[Air tightness (Pa·m 3 / s)]]> Interfacial strength (MPa) Porosity (%) Comparative Example 58.2 <![CDATA[1.0×10 -9 ]]> 9.8 2.1 Experiment 1 72.5 <![CDATA[8.5×10 -10 ]]> 15.2 1.8 Experiment 2 81.3 <![CDATA[6.2×10 -10 ]]> 18.7 1.5 Experiment 3 87.6 <![CDATA[3.7×10 -10 ]]> 24.3 1.3

[0081] Table 1

[0082] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:

[0083] As a high-molecular-weight polymer, PVP's long-chain molecules adsorb onto the surface of particles (CeO2, ZrO2, TiO2) to form a coating layer. This coating layer inhibits van der Waals forces between particles through physical barrier effects, preventing nanoparticle aggregation. The pyrrolidone groups (-NC=O) of PVP form hydrogen bonds with the hydroxyl groups (-OH) on the particle surface, increasing the binding energy to approximately 25 kJ / mol, enhancing adsorption stability and inhibiting particle aggregation. The aggregated particle size is reduced from >200 nm to <50 nm, improving particle dispersion uniformity. In an organic carrier (terpineol / butylcarbidol), PVP partially ionizes to generate a weak negative charge, further inhibiting particle aggregation through electrostatic repulsion.

[0084] In addition, PVP achieves high shear thinning behavior by adjusting the thixotropic index of the paste (1.8-2.2): high viscosity (15-20 Pa·s) at rest prevents particle sedimentation, and low viscosity during shearing is suitable for screen printing processes; PVP reduces the contact angle between the paste and the substrate, thereby improving the spreadability of the printed layer and ensuring line width accuracy.

[0085] Introducing PVP as a dispersant into glass slurry produces the following effects:

[0086] The particle dispersibility is further enhanced, and the CeO2 particles are uniformly dispersed (particle size distribution span <1.5), which reduces light scattering loss and improves the 810nm laser absorption efficiency. At the same time, the ZrO2 / TiO2 reinforcing phase is uniformly distributed, which inhibits the crystallization of the glass material (the crystallization temperature is stable at 420±10℃).

[0087] The PVP adsorption layer protects the oxygen vacancies on the CeO2 surface, prevents environmental oxidation, and maintains the defect state absorption peak in the range of 800-950 nm.

[0088] Laser sealing efficiency is improved, laser power requirements are reduced, energy concentration is increased, the heat-affected zone is reduced, and thermal damage to OLED devices is decreased; the porosity of the sealing layer is reduced, and the airtightness is further improved.

[0089] The storage period of the paste is extended, and the viscosity fluctuation is small; the yield of screen printing is improved.

[0090] V₂O₅-TeO₂ serves as the glass forming agent; TeO₂ exhibits high polarizability, reducing the rigidity of the glass network. V₂O₅ provides a bridging oxygen structure, enhancing the glass's thermal stability. BaO / ZnO acts as a network modifier. 2+ (Large ionic radius) reduces glass viscosity, Zn 2+ (Medium field strength) Balanced thermal expansion coefficient, suitable for OLED substrates; uniform CeO2 dispersion improves absorption efficiency per unit mass, further enhances sealing speed, strengthens particle-substrate interface bonding strength, and increases thermal shock resistance cycles; suitable for various printing processes (screen printing / inkjet / slot coating), expanding linewidth range; in this embodiment, the glass frit slurry uses a lead-free system (V2O5-TeO2-BaO-ZnO), avoiding the use of lead and heavy metal components, improving environmental performance; PVP dispersion and silane coupling agent form Si-OM (M=cordierite) chemical bonds on the cordierite surface, improving interface bonding strength, thereby enhancing density and reliability; laser sealing process is suitable for high-resolution, flexible OLED devices, providing an efficient, environmentally friendly, and highly reliable solution for OLED packaging.

[0091] Example 2: In Example 1, PVP was introduced into the glass slurry. Through the synergistic regulation of its micro-dispersion and macro-rheology, the problems of nanoparticle agglomeration, poor slurry stability, and weak interfacial bonding were solved. Its role is not limited to a dispersant. Through interface protection and rheological optimization, it promotes breakthroughs in lead-free, environmentally friendly, high-precision, and low-energy-consumption OLED packaging technology, providing a reliable solution for flexible displays and miniaturized devices. Further improvements were made based on Example 1 to further improve the overall performance of the glass slurry.

[0092] The dispersant also includes sulfonated lignin, which, by weight, comprises 0.5-1.2 parts;

[0093] PVP and sulfonated lignin are premixed and dissolved in 30% of the total terpineol. The mixture is stirred in a water bath at 50°C until completely dissolved to form a transparent colloid.

[0094] In step S32, the transparent colloid is added in three parts, with a 5-minute interval between each addition, and the mixture is pre-dispersed for 15 minutes at 2000 rpm using a planetary mixer.

[0095] S33. Add the remaining organic carrier, switch to ultrasonic dispersion mode (frequency 40kHz, power 300W) and treat for 10 minutes;

[0096] S34. Adjust the slurry rheological properties to a viscosity of 15-20 Pa·s (25℃) and a thixotropic index of 1.6-2.0.

[0097] Experiments were conducted on the above embodiments, based on the experiments in Example 1. The difference from Example 1 was that the dispersant also included sulfonated lignin. By weight, the amounts of sulfonated lignin added were 0.5 parts (Experiment 4), 1.2 parts (Experiment 5), and 0.85 parts (Experiment 6), respectively. The test results are shown in Table 2 below:

[0098] Laser absorption rate (%) <![CDATA[Air tightness (Pa·m 3 / s)]]> Interfacial strength (MPa) Porosity (%) Experiment 4 76.5 <![CDATA[7.2×10 -10 ]]> 17.3 1.6 Experiment 5 84.2 <![CDATA[3.5×10 -10 ]]> 26.5 1.0 Experiment Six 80.8 <![CDATA[5.1×10 -10 ]]> 22.1 1.2

[0099] Table 2

[0100] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:

[0101] The sulfonic acid group (-SO3H) of sulfonated lignin forms a charge-transfer complex with the carbonyl group (C=O) of PVP through an electron donor-acceptor interaction, increasing the adsorption energy from approximately 20 kJ / mol to approximately 45 kJ / mol, thus enhancing the stability of particle surface coating. The H group of the sulfonic acid group... + It forms hydrogen bonds with the N atoms of PVP (bond length ≈ C=O and -SO3 - They are bonded by electrostatic attraction;

[0102] In addition, the rigid aromatic rings (phenylpropane units) of sulfonated lignin are inserted between the flexible chains of PVP to form π-π stacks, which restrict the rotation of PVP chain segments, construct a three-dimensional cross-linking network, inhibit particle displacement, and prevent particle aggregation.

[0103] Third, the rigid structure of sulfonated lignin enhances the thixotropy of the slurry (thixotropic index 1.6-2.0), resulting in high viscosity (15-20 Pa·s) when the material is stationary, preventing particle sedimentation, and reducing viscosity under shearing to suit precision printing processes; sulfonated lignin forms hydrogen bonds with the hydroxyl groups on the surface of thermally stable ceramic fillers and cordierite, improving the interfacial bonding strength of the filler-matrix (≥22 MPa) and enhancing the overall mechanical properties of the material.

[0104] By further introducing sulfonated lignin, the improved dispersion stability allows the particles to be arranged more uniformly during sintering, reducing the formation of pores and improving the density of the sintered body. The improved interfacial bonding strength and the presence of the three-dimensional mesh lock structure enable the material to better resist the effects of thermal stress during thermal cycling, reducing the generation and propagation of cracks. The optimization of rheological properties allows the paste to be adapted to a wider range of printing process parameters, such as laser power and scanning speed, improving the flexibility and stability of the process.

[0105] Three-dimensional mesh locking inhibits the rotational agglomeration of ZrO2 / TiO2 / CeO2, further reducing the particle size distribution range. The ionization of sulfonated lignin sulfonic acid groups, combined with the weak negative charge of PVP, enhances electrostatic repulsion. The thixotropic index tolerance of the slurry is expanded to 1.6-2.0, improving the flexibility and stability of the process and making it suitable for industrial mass production. The aromatic ring structure of sulfonated lignin inhibits high-temperature particle migration and improves thermal cycling life. Sulfonated lignin is a bio-based material (degradation rate >90%), which, in synergy with lead-free systems, improves environmental performance.

[0106] The use of a single dispersant (PVP) in Example 1 has physicochemical limitations. With a single dispersant (PVP), the hydrogen bond adsorption energy is low, and there is a lack of rigid structural support, resulting in insufficient dispersion stability. Furthermore, the rheological control range is narrow, limiting industrial applications. In the long term, the reliability of interfacial bonding is limited. This example introduces sulfonated lignin to construct a synergistic system of PVP and sulfonated lignin, achieving a charge transfer complex and a three-dimensional mesh lock. This doubles the adsorption energy and structural stability, improves process flexibility and stability, enhances interfacial strength, and adapts to the high-precision OLED encapsulation requirements.

[0107] Example 3: Example 2 above introduces sulfonated lignin and PVP to construct a synergistic dispersion system. Through techniques such as charge transfer complex to enhance adsorption, three-dimensional grid locking structure to inhibit agglomeration, and dual-mode dispersion process and synergistic regulation of rheological properties, it solves the problems of nanoparticle agglomeration, poor slurry stability, weak interfacial bonding and insufficient process adaptability. It achieves uniform particle dispersion, optimized rheological properties, improved interfacial strength and environmentally friendly and low-energy-consumption encapsulation, and improves the reliability and process flexibility of OLED encapsulation. Further improvements are made based on Example 2 to further improve the overall performance of glass slurry.

[0108] The sulfonated lignin has a core-shell structure, wherein the core layer and the shell layer have different degrees of sulfonation, with the core layer having a sulfonation degree of 0.8 mmol / g and the shell layer having a sulfonation degree of 3.0 mmol / g.

[0109] The preparation method of the core-shell structured sulfonated lignin is as follows:

[0110] A1 Raw Material Pretreatment: The lignin raw material (alkali lignin, molecular weight 2000-5000Da) is pulverized to D50 = 50μm and washed with deionized water until pH = 6.0.

[0111] A2 core layer low sulfonation treatment: lignin and 5wt% dilute sulfuric acid were mixed at a mass ratio of 1:10 and stirred at 80℃ for 30 minutes, with the degree of sulfonation controlled at 0.8 mmol / g; after the reaction, the mixture was centrifuged, washed with water until neutral, and freeze-dried to obtain the low sulfonated core layer;

[0112] A3 shell high sulfonation treatment: The low sulfonated core layer was mixed with 20wt% concentrated sulfuric acid at a mass ratio of 1:5, and reacted at 120℃ with a gradient temperature increase (2℃ / min) for 1 hour to increase the degree of sulfonation to 3.0 mmol / g; dialysis purification (molecular weight cutoff 1000 Da), spray drying to obtain core-shell structured sulfonated lignin;

[0113] Among them, the core-shell structure sulfonated lignin has a particle size D50 of 200 nm and a core-shell structure thickness ratio of 1:2.

[0114] After premixing core-shell sulfonated lignin with PVP and adding it to the slurry system, the thixotropic index was dynamically adjusted to 1.5-2.2 to adapt to high-speed laser scanning (20mm / s).

[0115] Experiments were conducted on the above embodiments, based on the experiments in Example 2. The difference between Example 2 and Example 2 was that the sulfonated lignin had a core-shell structure, with different degrees of sulfonation between the core and shell layers: 0.8 mmol / g for the core layer and 3.0 mmol / g for the shell layer. The amounts of sulfonated lignin added were 0.5 parts (Experiment 7), 1.2 parts (Experiment 8), and 0.85 parts (Experiment 9), respectively. The test results are shown in Table 3 below.

[0116] Laser absorption rate (%) <![CDATA[Air tightness (Pa·m 3 / s)]]> Interfacial strength (MPa) Porosity (%) Experiment 7 85.2 <![CDATA[3.2×10 -10 ]]> 27.4 1.4 Experiment 8 90.1 <![CDATA[2.1×10 -10 ]]> 33.1 0.8 Experiment Nine 88.3 <![CDATA[2.7×10 -10 ]]> 30.4 1.2

[0117] Table 3

[0118] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:

[0119] By constructing core and shell structures with different degrees of sulfonation in sulfonated lignin, the overall performance of glass slurry is further improved. The low-sulfonation region (0.5-1.2 mmol / g) of the core layer of sulfonated lignin retains the rigid aromatic ring structure of lignin and forms a mechanical support framework with PVP chains through π-π stacking, thereby improving its mechanical properties. The high-sulfonation region (2.0-3.5 mmol / g) of the shell layer forms a gradient charge transfer network through dense sulfonic acid groups (-SO3H) and PVP carbonyl groups (C=O). Therefore, the adsorption energy increases from the core layer to the shell layer, thereby achieving dynamic response to shear or high temperature conditions. The high-sulfonic acid groups in the shell layer preferentially desorb under shear force or high temperature, releasing active sites and achieving self-regulating dispersion. This allows the material to automatically adjust its dispersion state according to changes in the external environment (shear force, high temperature, etc.) to maintain the best dispersion effect.

[0120] The gradient sulfonic acid group distribution expands the thixotropic index range, further improving process adaptability. Through further optimization of rheological properties, the flexibility and adaptability of production are enhanced. The aromatic rings in the core layer resist shear, while the sulfonic acid groups in the shell layer strengthen hydrogen bonding and electrostatic interactions, further improving the interfacial bonding strength.

[0121] By constructing core and shell structures with different degrees of sulfonation in sulfonated lignin, the overall performance of glass slurry can be further improved.

[0122] Improved dispersion stability: Gradient sulfonic acid groups respond to changes in process conditions, maintaining uniform dispersion even under high temperature or shear; core layer aromatic ring support reduces slurry settling rate;

[0123] Improved interface and density: Core layer aromatic ring-π stacking and shell layer hydrogen bonding / electrostatic bonding realize a multi-level bonding network, suppressing the propagation of interface cracks; sulfonic acid groups in structures with different degrees of sulfonation promote the orderly arrangement of particles, improve the uniformity of sintering, and further reduce porosity.

[0124] The sulfonated lignin in Example 2 is uniformly sulfonated, relying on a single chemical action and lacking functional partitioning and dynamic adjustment capabilities, resulting in limited performance in complex application environments. This example constructs core and shell structures with different degrees of sulfonation in the sulfonated lignin to combine the functional partitioning and dynamic response of the material. Through different sulfonation designs of the shell and shell, the material exhibits synergistically optimized performance at different scales.

[0125] Example 4: Example 3 above constructs a core and shell structure with different degrees of sulfonation in sulfonated lignin, which solves the problems of insufficient dispersion stability and limited process adaptability caused by uniform sulfonation in Example 2. It combines the functional zoning of materials with dynamic response, thereby achieving dynamic dispersion, reducing porosity, and enhancing interfacial bonding strength. It is a further improvement on Example 3 to further improve the overall performance of glass slurry.

[0126] The PVP includes short-chain PVP and long-chain PVP, wherein the short-chain PVP is 40kDa and the long-chain PVP is 50kDa, and the mass ratio of the short chain to the long chain is 3:1.

[0127] The PVP and core-shell sulfonated lignin are pre-dispersed before addition, specifically as follows:

[0128] Short-chain PVP was premixed with gradient sulfonated SL, dissolved in 30% of the total terpineol, and ultrasonically treated at 50°C (40 kHz) for 15 minutes.

[0129] Then add long-chain PVP and continue sonication for 10 minutes to form a graded dispersion colloid.

[0130] After adding the dispersing colloid to the slurry system, the thixotropic index was adjusted to 1.4-2.0 by rheological control to adapt to ultra-high-speed laser scanning (25mm / s).

[0131] Experiments were conducted on the above embodiments, based on the experiments in Embodiment 3. The difference between the experiments in Embodiment 3 and Embodiment 3 is that the PVP included short-chain PVP and long-chain PVP, wherein the short-chain PVP was 40kDa and the long-chain PVP was 50kDa, and the mass ratio of short-chain to long-chain was 3:1; the weight parts of PVP added were still 0.5 parts (Experiment 10), 2 parts (Experiment 11), and 1.25 parts (Experiment 12); the test results are shown in Table 4 below:

[0132] Laser absorption rate (%) <![CDATA[Air tightness (Pa·m 3 / s)]]> Interfacial strength (MPa) Porosity (%) Experiment 10 86.5 <![CDATA[2.8×10 -10 ]]> 29.3 1.1 Experiment Eleven 92.8 <![CDATA[1.5×10 -10 ]]> 36.8 0.6 Experiment Twelve 91.2 <![CDATA[2.0×10 -10 ]]> 33.5 0.8

[0133] Table 4

[0134] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:

[0135] By combining PVP molecular weight gradation with gradient sulfonation SL synergistic design, a synergistic effect of short-chain pore-filling wetting and long-chain elastic polymerization inhibition is achieved. The short-chain molecules have small molecular weights and fast diffusion rates, preferentially adsorbing to micropores (pore size <5nm) on the particle surface. They form hydrogen bonds (bond energy approximately 20kJ / mol) with CeO2 oxygen vacancies through terminal hydroxyl groups (-OH), filling surface defects, reducing roughness, and achieving rapid adsorption and wetting. At the same time, the short chains rapidly penetrate into the interparticle gaps under shear force, reducing local stress concentration. The long-chain molecules form multiple hydrogen bonds (bond energy approximately 35kJ / mol) with the sulfonic acid groups of the gradient SL through the pyrrolidone ring of the main chain, increasing the adsorption layer thickness, inhibiting particle aggregation, and further strengthening steric hindrance. Meanwhile, the long chains wrap around the particles to form a three-dimensional elastic network, resisting particle migration at high temperatures.

[0136] Secondly, short-chain PVP fills the gaps between aromatic rings in the gradient SL core layer, forming a dense structure through physical entanglement and hydrogen bonding, thus creating a dense anchoring layer and achieving rigid support. The strong interaction between the aromatic ring skeleton and PVP endows the material with high strength and the ability to withstand high stress. The chemical bonds (such as hydrogen bonds) between short-chain PVP and aromatic rings break under stress, dissipating local stress through dynamic dissociation and recombination of bonds, avoiding structural damage caused by stress concentration. Meanwhile, long-chain PVP crosslinks with the sulfonic acid groups on the surface of the gradient SL layer, forming a dynamic elastic layer. This allows the surface active sites to be released through chain segment movement when shear force or temperature changes, achieving dynamic response. The chain segment slip of long-chain PVP dissipates energy through conformational adjustment of the molecular chain, dispersing local stress to a larger area, preventing crack propagation, and achieving long-range stress buffering.

[0137] Third, short chains improve wettability (contact angle <15°), while long chains enhance shear thinning (thixotropic index 1.4-2.0), making them compatible with ultra-high-speed laser scanning (25mm / s), further improving industrial adaptability and enhancing production flexibility and adaptability. In addition, short chains fill micropores to reduce interface defects, while long chains and gradient SL synergistically enhance interfacial bonding strength.

[0138] The overall performance of the glass slurry was further improved by combining PVP molecular weight classification with gradient sulfonation SL.

[0139] Stable dispersion: Short-chain PVP fills the voids and reduces roughness, while long-chain PVP inhibits agglomeration at high temperatures, further reducing the particle size distribution range and improving dispersion uniformity.

[0140] Interface and density: Short chains reduce interface defects, long chains synergistically bond with gradient SL, further improving interface strength, reducing sintering porosity, and improving airtightness after laser sealing.

[0141] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-energy laser sealing OLED glass slurry, characterized in that, The following components are included in parts by weight: Basic glass material: V2O5 30-60 parts, TeO2 20-40 parts, BaO 5-30 parts, ZnO 5-15 parts; Enhancement system: ZrO2 5-10 parts, TiO2 5-10 parts; Photothermal conversion agent: CeO2 0.5-2 parts; Thermally stabilized ceramic filler: 5-15 parts cordierite; Dispersant: 0.5-2 parts polyvinylpyrrolidone, 0.5-1.2 parts sulfonated lignin; Organic carrier: 15-25 parts ethyl cellulose, 5-10 parts terpineol, 5-10 parts butyl carbitol.

2. The OLED glass slurry for low-energy laser sealing as described in claim 1, characterized in that, The glass transition temperature of the base glass material is 340±5℃, and the crystallization temperature is 420±10℃.

3. The OLED glass slurry for low-energy laser sealing as described in claim 1, characterized in that, Sulfonated lignin has a core-shell structure with a core sulfonation degree of 0.8 mmol / g and a shell sulfonation degree of 3.0 mmol / g, resulting in a core-shell thickness ratio of 1:

2.

4. The OLED glass slurry for low-energy laser sealing as described in claim 3, characterized in that, The preparation of the core-shell structure involves treating lignin sequentially with 5wt% dilute sulfuric acid at 80℃ for 30 minutes to sulfonate the core layer, followed by a gradient heating treatment with 20wt% concentrated sulfuric acid at 120℃ for 1 hour to sulfonate the shell layer. After dialysis purification, the lignin is spray-dried to obtain the final product.

5. The OLED glass slurry for low-energy laser sealing as described in claim 1, characterized in that, Polyvinylpyrrolidone (PVP) includes short-chain and long-chain forms, with the short chain having a capacity of 40 kDa and the long chain having a capacity of 50 kDa. The mass ratio of the short chain to the long chain is 3:

1.

6. The OLED glass slurry for low-energy laser sealing as described in claim 1, characterized in that, Cordierite was surface modified with silane coupling agent KH-550, with a mass ratio of cordierite to silane coupling agent of 95:

5.

7. The OLED glass slurry for low-energy laser sealing as described in claim 1, characterized in that, The viscosity of the slurry at 25°C is 15-20 Pa·s, and the thixotropic index is 1.4-2.

2.

8. A method for preparing a low-energy laser sealing OLED glass slurry as described in any one of claims 1-7, characterized in that, Specifically, the steps include the following: S1. Basic glass material synthesis: V2O5, TeO2, BaO and ZnO are mixed, melted and quenched, and then ground until D50≤2μm and particle size distribution span<1.5; S2. Cordierite surface modification: Cordierite is mixed with a silane coupling agent and dried to obtain surface-modified cordierite; S3. Slurry preparation: The base glass material, ZrO2, TiO2, CeO2 and modified cordierite are mixed, polyvinylpyrrolidone and sulfonated lignin pre-dispersion are added, and then mixed with the organic carrier. The slurry is prepared by planetary stirring and ultrasonic dispersion.

9. The method for preparing the low-energy laser sealing OLED glass slurry as described in claim 8, characterized in that, The pre-dispersion is prepared by premixing polyvinylpyrrolidone and core-shell sulfonated lignin, dissolving them in terpineol at 30% of the total terpineol content, and then ultrasonically treating them at 50°C for 15-25 minutes to form the pre-dispersion.

10. The method for preparing the low-energy laser sealing OLED glass slurry as described in claim 8, characterized in that, The paste is applied to the OLED substrate by screen printing, with a line width of 50μm and a thickness of 10μm; the laser sealing uses an 810nm fiber laser with a power of ≤8W and a scanning speed of 10-25mm / s.

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